Herman hasn't been looking well.
In the middle of jam-making and cake-baking a few days ago, I asked my husband to attend to Herman and add flour and water. Unfortunately I wasn't too specific about amounts. Not enough flour and/or too much water left a bit of a mess.
In an attempt to salvage Herman, I drained off the beer-like fluid and added some flour and sugar. It now seems to be bubbling nicely again - fingers crossed!